Canning Tomatoes Is Easy

Canning Tomatoes Is Easy: Step by Step Process

If you love to cook spaghetti sauce, lasagna, pizza, chili, or anything else that calls for a tomato-based sauce, there’s nothing like home preserved tomatoes to take your cooking from ordinary to extraordinary.

This September, why not preserve your own tomatoes. Preserving is easy and can be done by anyone. All you need is to block off a day (or two) and acquire some basic equipment and a few ingredients. A helper or two will also make the job easier and more enjoyable.

Once you preserve your own tomatoes you will never want to open another tin or store-bought tomato jar again.

Ingredients you will need:

• San Marzano Tomatoes. Purchase by the bushel from a local vendor. In Toronto, we recommend Sandy’s Farms on Weston Road in Woodbridge. Sandy’s charges $20 per bushel of tomatoes plus $1 deposit for the bushel. Find out from the vendor how ripe they are. The tomatoes may need to be laid out in your garage for a few days to ripen and to maximize their flavour.
• Kosher Salt.
• Lemon Juice.

Equipment you will need:

If you are just starting out you may want to borrow some items from family or a friend. Once you have tried your hand at preserving tomatoes, you will want to go out and purchase these items to have in your arsenal to re-use every year.

• 1-quart Mason Jars. You will need approximately 14-16 jars for each bushel of tomatoes you process. Wash your jars in the dishwasher. Once you start processing your tomatoes, keep the jars warm in a 210F oven until you are ready to fill them with pressed tomatoes.
• Mason jar lids and screw on caps. Boil the lids for 2-5 mins before using. The caps do not need to be pre-boiled.
• Water Canner. This is a large pot for boiling your filled jars of tomatoes.
• Metal Rack. This will be used in the water canner to keep water flowing between the jars. Makes it easy to raise and lower jars in and out of the large canning pot.
• Heavy duty rubber gloves.
• Tomato press. Electric or manual. A really good press will set you back $600+ or so. In Toronto, you can buy one from Consiglio’s Kitchenware. However, a press is optional! Read below to learn how to preserve tomatoes without a press.
• Lots of Pots/Bowls. Do not use aluminum when cooking tomatoes. 

Steps to canning tomatoes (using tomato press and hot water bath):

1. Fill your kitchen sink with fresh water and add tomatoes. Wash tomatoes well. Cut out the stem, remove any bad parts, and halve tomatoes. Place in strainer and mix in some salt. Let sit for 1 hour or so to drain out excess water..
2. Put tomatoes in large stainless steel pot on low heat to soften. I recommend not using anything larger than a 32L pot if you intend to do a large batch on your stove top. Keep stirring and raise the heat as the tomatoes continue to break down. Mash down with a wooden spoon to help speed up the process. This step should take at least 1 hour. Note: This step is very important for two reasons. First, when tomatoes are cut or pressed, they release an enzyme causing the liquid to separate from the pulp. If you were to press them without heating them in the pot and then put them straight into your jars, your final jars would look like the last picture in the article below. Second, it’s a lot harder to press tomatoes that haven’t been heated and softened. There is nothing unsafe about eating separated tomatoes, they just don’t look as nice.
3. When the tomatoes are very soft and mushy, add them to the press.
4. The seeds and skins that are ejected from the press need to be pressed two more times (with equal amounts of sauce) so that all of the juice is fully extracted. Compost the tomato scraps.
5. Optional: Return the tomatoes to the pot and boil for 1.5 hours. This will help remove excess water and create a thicker sauce.
6. Add the pressed tomatoes to the warmed jars. Leave about one centimetre from the top. Add in 1/2 tsp of kosher salt and 1 tbsp of lemon juice. (you won’t taste either in the finished product). Put on the freshly boiled lid and screw on the cap snugly – but not too tightly.
7. Fill the water canner half with water and put to boil. Carefully add in the jars. Lower the metal rack and add more water until the jars are covered by 1 inch of water. Close the lid. As soon as the water starts to boil, reduce heat to medium (keep it at a gentle boil) and set timer for 45 minutes. I usually cover the canner with a thick towel to keep the heat in.
8. Use the rubber gloves to lift the metal rack and remove jars. I put the jars in the corner of my kitchen on a thick bath towel and cover with another towel. I leave overnight until they have fully cooled down.
9. The lids will start to “pop” as the jars begin cooling. Check all the lids the next day. If you see them indented and you cannot push down that means you have a perfect seal. When the jars are cool, you can store them and use them right of way. Jars that didn’t seal, you will need to use in the next couple of days.

Washing and Prepping San Marzano Tomatoes

Freshly preserved tomato jars are ready for storage.

Optional: Canning tomatoes without a canner / hot water bath (Step 6 above)

Believe it or not, but it is possible to can tomatoes safely without using a canner and hot water bath. Depending on how many tomatoes you need to preserve, this could save you HOURS of time.

To do so, follow the process above but instead of putting the pressed tomatoes straight into the jar, it is important that you follow these steps:

• After pressing, return tomatoes to the pot to boil. I usually let them boil for 1.5 hours as I like thicker sauce.
• While the sauce is boiling, put them in the warmed jar, add the salt and lemon juice and screw on the lid and cap. Do this step very quickly so there’s no time for the sauce to cool! Flip jars upside down and put them under a thick set of blankets to cool slowly.
• The next day, you can flip the jars over. If any have leaked, you know they weren’t sealed properly. Double check by pressing the lid and making sure there’s no ‘bounce back’.

Steps to canning tomatoes (no tomato press):

If you have a small batch and don’t want to invest in a tomato press, you can try this method.

1. Fill your kitchen sink with fresh water and add tomatoes.
2. Add 10-12 tomatoes to a pot of boiling water. As soon as the skins start to crack, take the tomatoes out with a sieve.
3. Put the hot tomatoes in a bowl of ice water. Take a small kitchen knife and start to peel off the skin, stem and any bad parts. I find that wearing clean rubber gloves helps protect the hands from the heat.
4. Add the cleaned tomatoes to the washed jars. (The jars can be cold). Leave about one centimetre from the top. Add in 1/2 tsp of kosher salt and 1 tbsp of lemon juice. (you won’t taste either in the finished product). Put on the freshly boiled lid and screw on the cap snugly – but not too tightly.
5. See steps 7-9 above.

For years we peeled our tomatoes by hand but recently switched to using a tomato press.  I find that the tomato press does make the job much easier and gives a nice smooth puree without seeds.

Canning tomatoes is a lot of work but you will appreciate the taste and convenience of having your own jars on hand when you cook throughout the year. You can even make a few extra jars and give as a gift for friends and family.

Happy canning!

Author: Karen Makedon